Method for constructing large-area superlattice monolayer film in one step based on chemical cross-linking method and application thereof
By constructing large-area superlattice monolayer films through chemical crosslinking, the challenges of stability and macroscopic preparation of nanoparticle superlattices were solved, and controllable crosslinking and dense arrangement between gold nanoparticles were achieved, forming superlattice monolayer films with good stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HANGZHOU NORMAL UNIVERSITY
- Filing Date
- 2026-01-14
- Publication Date
- 2026-05-29
AI Technical Summary
The stability of existing nanoparticle superlattices is a problem, especially the instability of superlattices constructed by physical interactions and the difficulty in preparing them on a large scale. Superlattices constructed by chemical cross-linking affect the electrical, magnetic and optical properties between nanoparticles.
A chemical cross-linking method was used to modify gold nanoparticles with mercapto polyethylene glycol and 4-ATP. The active ligands were then activated by ultraviolet light, which caused carbon-hydrogen insertion reactions between the ligands to form covalent bonds, thus constructing a large-area dense superlattice monolayer film.
Controllable cross-linking between gold nanoparticles was achieved, forming a dense and stable superlattice monolayer film with adjustable spacing, an area of over 3 cm2, and a particle spacing as low as 1.0 nm.
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Figure CN122105634A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanomaterials technology, specifically relating to a method for constructing large-area superlattice monolayer films in one step based on chemical crosslinking and its application. Background Technology
[0002] Nanoparticle superlattices are mesoscopic condensed matter composed of nanocrystals and possessing crystalline symmetry. They represent a new class of crystalline materials, exhibiting collective properties distinct from bulk crystals, isolated nanocrystals, and even disordered nanocrystals. For example, they display ultrafast nonlinear optical response, broadband, and tunable light absorption. Based on these properties, nanoparticle superlattices hold broad application prospects in various fields, including catalysis, sensing and detection, optoelectronic devices, and energy storage.
[0003] Methods for constructing nanoparticle superlattices are of great significance for the fabrication of functional devices. Existing methods for constructing nanoparticle superlattices include gas-liquid, liquid-liquid, and gas-liquid-solid interface self-assembly, emulsion interface self-assembly, etc. In the assembly process, the basic units spontaneously associate into superlattices through weak interaction forces (such as van der Waals forces, hydrogen bonds, electrostatic forces, hydrophobic forces, etc.), which belong to superlattices constructed by physical processes; and superlattices that are stable by forming strong interaction forces through chemical reactions, which belong to superlattices constructed by chemical cross-linking processes.
[0004] Due to the weak interparticle interactions, superlattices constructed through physical processes are quite unstable and easily destroyed, exhibiting problems such as fragility, difficulty in large-scale macroscopic fabrication, and difficulty in self-support. While superlattices constructed through chemical cross-linking endow them with stable properties, the coupling interactions between adjacent nanoparticles can affect the electrical, magnetic, and optical properties of the resulting nanostructures. Therefore, the development and research of methods for preparing nanoparticle superlattices are of crucial significance in fields such as nanoelectronics and catalysis.
[0005] Chinese patent document CN118497191A discloses a method for preparing a dynamically controllable nanoparticle superlattice based on a DNA origami crystal template. The invention includes the following steps: (1) synthesizing various DNA origami framework structures with specific linking and selective loading capabilities; (2) modifying gold nanoparticles with functionalized thiol DNA chains on their surface; (3) synthesizing a multi-element co-crystallized DNA origami crystal substrate loaded with gold nanoparticles at specific sites in a one-step process; and (4) controlling the order and timing of adding different DNA segments to the washed substrate, followed by isothermal heat treatment, to obtain a dynamically controllable nanoparticle superlattice based on a DNA origami crystal template. This invention enables the nanoparticle superlattice to transform between multiple states in a dynamically controllable manner, but structural stability issues still exist.
[0006] Chinese patent document CN115233310A discloses a two-dimensional superlattice film modified with cyclic polyethylene glycol. The two-dimensional superlattice film is a monolayer structure composed of a series of cyclic polyethylene glycol-modified nanoparticles (gold, silver, platinum or silica nanoparticles) with uniform morphology, which are assembled and arranged in an orderly manner. The corresponding nanoparticles exhibit a highly ordered hexagonal stacking periodic arrangement. This invention modifies the nanoparticles with cyclic polyethylene glycol molecular brushes, so that the cyclic polymer brushes on the surface of adjacent nanoparticles permeate each other, forming a physical entanglement similar to a "molecular knot", thereby significantly improving the structural stability of the two-dimensional superlattice film. However, the physical entanglement is greatly affected by the environment, and the spacing between nanoparticles is large.
[0007] To address the stability issues of nanoparticle superlattices and construct self-supporting, dense superlattice monolayers, it is urgent to develop novel chemical crosslinking construction methods. Summary of the Invention
[0008] This invention provides a method for constructing a large-area superlattice monolayer film in one step based on chemical crosslinking, which can achieve controllable crosslinking between gold nanoparticles and construct a dense superlattice monolayer film with reduced spacing based on physical-chemical synergy.
[0009] The specific technical solution adopted is as follows: A method for constructing a large-area superlattice monolayer film in one step based on chemical crosslinking includes the following steps: (1) Using mercapto polyethylene glycol as ligand A, gold nanoparticles were modified sequentially with ligand A and 4-ATP; after activating the carboxyl group of 4-azido-2,3,5,6-tetrafluorobenzoic acid, it was subjected to an amidation reaction with the 4-ATP modified on the gold nanoparticles to generate ligand B, thus preparing gold nanoparticles modified with two ligands. (2) The gold nanoparticles modified with dual ligands were dispersed in toluene and then transferred to the diethylene glycol subphase. After the toluene evaporated completely, a gold nanoparticle film was obtained on the diethylene glycol interface. The gold nanoparticle film was subjected to ultraviolet light irradiation to induce hydrocarbon insertion reaction between ligand A and ligand B, thereby reducing the spacing between the gold nanoparticles and obtaining the large-area superlattice monolayer film.
[0010] This invention is based on a chemical cross-linking strategy. By designing active ligands for gold nanoparticles, ligand A (thiol polyethylene glycol) and ligand B (formed by the amidation reaction of 4-ATP and 4-azido-2,3,5,6-tetrafluorobenzoic acid with activated carboxyl groups) are grafted onto the gold nanoparticles. After the nanoparticles are assembled into a film, the active ligands are activated by ultraviolet light, causing a hydrocarbon insertion reaction between ligands A and B to form covalent bonds and stabilize the superlattice. This reduces the spacing between the gold nanoparticles, causing the gold film to shrink and form a large-area, dense, long-range ordered gold nanoparticle superlattice monolayer. By adjusting the grafting amount of ligands A and B, the spacing between the gold nanoparticles can be controlled, thereby achieving controllable cross-linking between the gold nanoparticles.
[0011] Preferably, the unmodified gold nanoparticles are prepared by a seed growth method. A seed solution is prepared using chloroauric acid, sodium borohydride, and hexadecyltrimethylammonium bromide (CTAB) as raw materials. Then, the gold nanoparticles are further prepared by growing the gold seeds using the seed solution, ascorbic acid, hexadecyltrimethylammonium chloride (CTAC), and chloroauric acid as raw materials.
[0012] Furthermore, the unmodified gold nanoparticles have a particle size of 20-50 nm, and the average molecular weight of thiol-based polyethylene glycol (SH-PEG) is 1800-2000 g / mol. Specifically, thiol-based polyethylene glycol can be selected with a single thiol terminal. If the average molecular weight of thiol-based SH-PEG is too small, the aqueous nanoparticles will be unable to commutate to the toluene phase, thus preventing the assembly of a gold film at the interface.
[0013] Preferably, sodium chloride aqueous solution, mercapto-polyethylene glycol aqueous solution, and 4-ATP ethanol solution are added sequentially to gold nanoparticles. After sonication, n-butanol is added, followed by centrifugation and washing to complete the modification of gold nanoparticles by ligand A and 4-ATP. The molar ratio of sodium chloride, mercapto-polyethylene glycol, and 4-ATP is 3000:5-15:25-100. Sodium chloride acts as a shield for electrostatic charges, accelerating the modification of mercapto-polyethylene glycol and 4-ATP on the nanoparticles.
[0014] Preferably, EDC and NHS are used as activators to activate the carboxyl group of 4-azido-2,3,5,6-tetrafluorobenzoic acid, converting it into an active intermediate, which then undergoes an amidation reaction with 4-ATP to synthesize ligand B.
[0015] Preferably, in a tetrahydrofuran system, activated 4-azido-2,3,5,6-tetrafluorobenzoic acid undergoes an amidation reaction with 4-ATP modified on gold nanoparticles. The reaction is continuously stirred, the reaction temperature is 20-30 °C, and the reaction time is 8-14 h.
[0016] Preferably, the ultraviolet light irradiation conditions are: wavelength 254 nm, optical power 65-70 mW / cm². 2 The irradiation time is 1.0-2.5 h.
[0017] The present invention also provides a superlattice monolayer film prepared by the method described above for one-step construction of a large-area superlattice monolayer film based on chemical crosslinking.
[0018] The superlattice monolayer film is composed of gold nanoparticles with a spacing of 1.0-1.5 nm between them. The spacing between the gold nanoparticles in this superlattice monolayer film is adjustable, and can be as low as 1.0 nm, exhibiting a dense structure and good structural stability.
[0019] The present invention also provides the application of the superlattice monolayer film in the field of detection or sensing.
[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention designs active ligands for gold nanoparticles and grafts ligand A (thiol polyethylene glycol) and ligand B (formed by amidation reaction of 4-ATP and 4-azido-2,3,5,6-tetrafluorobenzoic acid with activated carboxyl groups) onto gold nanoparticles to replace traditional molecular crosslinking agents. By adjusting the grafting density of ligand A and ligand B, the steric hindrance is affected, and the traditional uncontrollable crosslinking is transformed into controllable crosslinking.
[0021] (2) In this invention, after the dual-ligand modified gold nanoparticles are assembled into a film, the active ligands are activated by ultraviolet light. A hydrocarbon insertion reaction occurs between ligand A and ligand B. Based on the physical effect of superlattice domain healing through interfacial self-assembly and the hydrocarbon insertion chemical reaction of ligands A and B, a large-area, dense, long-range ordered gold nanoparticle superlattice monolayer film with an area of up to 3 cm² is prepared. 2 The spacing between gold nanoparticles is as low as 1.0 nm, resulting in a dense structure with good structural stability. Attached Figure Description
[0022] Figure 1 This is a TEM image of the gold nanoparticles before modification in Example 1.
[0023] Figure 2 These are TEM images of the gold nanoparticle film in Example 1 that were not subjected to ultraviolet light irradiation, where the scale bar in a is 1 μm, in b is 100 nm, and in c is 50 nm.
[0024] Figure 3 This is a macroscopic image of the gold nanoparticle film in Example 1 that was not subjected to ultraviolet light irradiation.
[0025] Figure 4These are TEM images of the superlattice monolayer film after ultraviolet light irradiation treatment in Example 1, where the scale bar in a is 1 μm, in b is 100 nm, and in c is 50 nm.
[0026] Figure 5 This is a macroscopic image of the superlattice monolayer film after ultraviolet light irradiation treatment in Example 1.
[0027] Figure 6 These are the statistical results of the interparticle spacing of the gold nanoparticle film in Example 1 that was not subjected to ultraviolet light irradiation.
[0028] Figure 7 These are the statistical results of the interparticle spacing of the superlattice monolayer film after ultraviolet light irradiation treatment in Example 1.
[0029] Figure 8 This is a TEM image of the superlattice monolayer film after ultraviolet light irradiation treatment in Example 2.
[0030] Figure 9 This is a TEM image of the superlattice monolayer film after ultraviolet light irradiation treatment in Example 3.
[0031] Figure 10 The results are Raman monitoring results of the gold nanoparticle film during the ultraviolet light irradiation crosslinking process in Example 1. Detailed Implementation
[0032] To make the objectives, features, and advantages of this invention more apparent and understandable, a detailed description is provided below through specific embodiments. Many specific details are set forth in the following description to provide a thorough understanding of the invention. However, the invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below. Technical features in various embodiments of the invention can be combined appropriately without mutual conflict.
[0033] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer. Contents not described in detail in this specification are prior art known to those skilled in the art. Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.
[0034] Example 1 (1) Preparation of gold nanospheres Gold nanospheres were prepared using the classic crystal seeding method and seed growth method.
[0035] Synthesis of gold nanosphere seeds: 9.9 mL of 0.1 M hexadecyltrimethylammonium bromide (CTAB) and 100 μL of 25 mM chloroauric acid (HAuCl4) were added to a small glass bottle and stirred for 3 min. Then, 600 μL of freshly prepared sodium borohydride (NaBH4) in 10 mM ice water was added, and the mixture was stirred at 300 rpm for 3 min. The mixture was then allowed to stand at 30°C for 3 h to obtain the gold nanosphere seed solution.
[0036] Preparation of small-diameter gold nanospheres: 80 mL of 200 mM hexadecyltrimethylammonium chloride (CTAC), 60 mL of 100 mM ascorbic acid (AA), and 2 mL of gold nanosphere seed solution were added sequentially to a 250 mL beaker. The mixture was stirred at 600 rpm for 3-5 min. Then, 80 mL of 0.5 mM HAuCl4 was added at once while stirring at 600 rpm. The mixture was stirred at 300 rpm for 15 min to obtain a gold nanosphere solution with an average particle size of approximately 10 nm. 15 mL of this gold nanosphere solution was centrifuged at 16000 rpm for 20 min, and the precipitate was redispersed in 2.5 mL of 10 mM CTAC to obtain the growth solution.
[0037] Preparation of large-diameter gold nanospheres: 20 mL of 100 mM CTAC and 750 μL of growth solution were added to a 250 mL beaker. After mixing and sonicating for 10 min, 1.3 mL of 10 mM AA was added, and the mixture was stirred in a 30°C water bath for 1 min. 30 mL of 0.5 mM HAuCl4 was added dropwise to the beaker at a flow rate of 20 mL / h until a color change occurred (from purple to pink). The addition was stopped, and stirring was continued for 5 min to obtain the gold nanosphere solution. TEM images of the gold nanospheres are shown below. Figure 1 As shown, the gold nanospheres are uniform in size, with a particle size of 30–34 nm.
[0038] (2) Activation of 4-azido-2,3,5,6-tetrafluorobenzoic acid Place a brown, light-proof glass bottle in a magnetic immersion chamber. Dissolve 70 mg of 4-azido-2,3,5,6-tetrafluorobenzoic acid, 200 μL of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, and 100 mg of NHS N-hydroxysuccinimide in 4 mL, 2 mL, and 3 mL of tetrahydrofuran, respectively. Sonicate the solutions for a period of time to promote dispersion and dissolution. Then, add the 4-azido-2,3,5,6-tetrafluorobenzoic acid solution and the 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide solution to the brown, light-proof glass bottle. Stir at 400 rpm for 5 min. Add the sodium salt solution of N-hydroxythiosuccinimide and stir at 400 rpm for 2 h to obtain an activated intermediate solution of 4-azido-2,3,5,6-tetrafluorobenzoic acid.
[0039] (3) Preparation of dual-ligand modified gold nanoparticles Weigh 10 mL of the gold nanosphere solution obtained in step (1), centrifuge at 12000 rpm for 10 min, remove the supernatant, add 10 mL of deionized water to the precipitate, centrifuge at 12000 rpm for 10 min, remove the supernatant, and then add 200 μL of 15 mM sodium chloride aqueous solution, 10 μL of 1 mM SH-PEG (average molecular weight of 2000 g / mol) aqueous solution, and 5.1 μL of 10 mM 4-ATP ethanol solution dropwise to it, and then sonicate. After sonication, 5 mL of n-butanol was added to form a solid solution. The solid solution was transferred to a 2 mL centrifuge tube, and the excess supernatant was removed. The tube was centrifuged at 12000 rpm for 10 min, and the supernatant was removed and dispersed in 1 mL of water. The tube was centrifuged at 12000 rpm for 10 min, and the supernatant was removed and dispersed in 1 mL of THF. The tube was centrifuged at 12000 rpm for 10 min, and the supernatant was removed and dispersed in 1 mL of THF. The solution was added dropwise to the activation intermediate solution of (2), sealed with film and foil, and stirred at 400 rpm for 14 hours at 25°C to obtain a solution of gold nanoparticles modified with dual ligands.
[0040] (4) Preparation of superlattices by chemical cross-linking A solution of dual-ligand modified gold nanoparticles was centrifuged at 10,000 rpm for 2 min, the supernatant was discarded, and 5 mL of methanol solution containing dissolved sodium chloride (concentration 10 mg / mL) was added. The mixture was centrifuged at 2,000 rpm for 2 min, the supernatant was collected, and centrifuged at 10,000 rpm for 10 min. 5 mL of tetrahydrofuran solution was added, and the mixture was centrifuged at 10,000 rpm for 10 min. The supernatant was dispersed in 1 mL of toluene solution. This solution was then added dropwise to a 20 mL polytetrafluoroethylene tube containing diethylene glycol. The tube was capped and allowed to evaporate completely. After the toluene had evaporated, a gold nanoparticle film was obtained. The TEM image of the gold nanoparticle film is shown below. Figure 2As shown in ac, the macroscopic photo is as follows Figure 3 As shown, the statistical results of the spacing between gold nanoparticles are as follows: Figure 6 As shown.
[0041] Subsequently, a 254 nm ultraviolet lamp with an optical power of 70 mW / cm² was used. 2 The gold nanoparticle film was irradiated for 2.5 hours, causing the gold film to shrink and yielding a chemically cross-linked superlattice monolayer film. A TEM image of this superlattice monolayer film is shown below. Figure 4 As shown in ac, the macroscopic photo is as follows Figure 5 As shown, the statistical results of the spacing between gold nanoparticles are as follows: Figure 7 As shown, the gold nanospheres in this superlattice monolayer film exhibit long-range order and dense arrangement.
[0042] During the crosslinking process under ultraviolet light irradiation, the Raman monitoring results of the gold nanoparticle film are as follows: Figure 10 As shown, the nanoparticle superlattice gradually heals as the cross-linking process proceeds, eventually forming a dense superlattice. The orderliness of the superlattice affects the Raman signal, and the 4-ATP signal peak on the nanoparticles gradually strengthens (1075 cm⁻¹). -1 1585 cm -1 ).
[0043] Example 2 The only difference between this embodiment and Example 1 is that, in the preparation of the dual-ligand modified gold nanoparticles, 200 μL of 15 mM sodium chloride aqueous solution, 5 μL of 1 mM SH-PEG (molecular weight 2000 g / mol) aqueous solution, and 2.5 μL of 10 mM 4-ATP ethanol solution were used. All other steps and parameters were the same as in Example 1. After UV irradiation, the TEM image of the obtained superlattice monolayer film is shown below. Figure 8 As shown.
[0044] Example 3 The only difference between this embodiment and Example 1 is that, in the preparation of the dual-ligand modified gold nanoparticles, 200 μL of 15 mM sodium chloride aqueous solution, 15 μL of 1 mM SH-PEG (molecular weight 2000 g / mol) aqueous solution, and 10 μL of 10 mM 4-ATP ethanol solution were used. All other steps and parameters were the same as in Example 1. After UV irradiation, the TEM image of the obtained superlattice monolayer film is shown below. Figure 9 As shown.
[0045] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for constructing a large-area superlattice monolayer film in one step based on chemical crosslinking, characterized in that, Includes the following steps: (1) Using mercapto polyethylene glycol as ligand A, gold nanoparticles were modified sequentially with ligand A and 4-ATP; After activating the carboxyl group of 4-azido-2,3,5,6-tetrafluorobenzoic acid, it undergoes an amidation reaction with 4-ATP modified on gold nanoparticles to generate ligand B, thus preparing dual-ligand modified gold nanoparticles. (2) The gold nanoparticles modified with dual ligands were dispersed in toluene and then transferred to the diethylene glycol subphase. After the toluene evaporated completely, a gold nanoparticle film was obtained on the diethylene glycol interface. The gold nanoparticle film was subjected to ultraviolet light irradiation to induce hydrocarbon insertion reaction between ligand A and ligand B, thereby reducing the spacing between the gold nanoparticles and obtaining the large-area superlattice monolayer film.
2. The method for constructing a large-area superlattice monolayer film in one step based on chemical crosslinking according to claim 1, characterized in that, The unmodified gold nanoparticles have a particle size of 20-50 nm, and the average molecular weight of mercapto polyethylene glycol is 1800-2200 g / mol.
3. The method for constructing a large-area superlattice monolayer film in one step based on chemical crosslinking according to claim 1, characterized in that, Sodium chloride aqueous solution, mercapto polyethylene glycol aqueous solution and 4-ATP ethanol solution were added sequentially to gold nanoparticles. After sonication, n-butanol was added, followed by centrifugation and washing to complete the modification of gold nanoparticles by ligand A and 4-ATP. The molar ratio of sodium chloride, mercapto polyethylene glycol and 4-ATP was 3000:5-15:25-100.
4. The method for constructing a large-area superlattice monolayer film in one step based on chemical crosslinking according to claim 1, characterized in that, The carboxyl group of 4-azido-2,3,5,6-tetrafluorobenzoic acid was activated using EDC and NHS as activators.
5. The method for constructing a large-area superlattice monolayer film in one step based on chemical crosslinking according to claim 1, characterized in that, In a tetrahydrofuran system, activated 4-azido-2,3,5,6-tetrafluorobenzoic acid was subjected to an amidation reaction with 4-ATP modified on gold nanoparticles. The reaction was continuously stirred, the reaction temperature was 20-30 °C, and the reaction time was 8-14 h.
6. The method for constructing a large-area superlattice monolayer film in one step based on chemical crosslinking according to claim 1, characterized in that, The conditions for ultraviolet light irradiation treatment are: wavelength 254 nm, optical power 65-70 mW / cm². 2 The irradiation time is 1.0-2.5 h.
7. The superlattice monolayer film prepared by the method for constructing a large-area superlattice monolayer film in one step based on chemical crosslinking according to any one of claims 1-6.
8. The superlattice monolayer film according to claim 7, characterized in that, The superlattice monolayer film is composed of gold nanoparticles with a spacing of 1.0-1.5 nm between them.
9. The application of the superlattice monolayer film according to claim 7 or 8 in the field of detection or sensing.